// Copyright 2014 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef MEDIA_CAST_NET_UDP_TRANSPORT_H_
#define MEDIA_CAST_NET_UDP_TRANSPORT_H_

#include <stdint.h>

#include <memory>

#include "base/macros.h"
#include "base/memory/ref_counted.h"
#include "base/memory/weak_ptr.h"
#include "base/values.h"
#include "build/build_config.h"
#include "media/cast/cast_environment.h"
#include "media/cast/net/cast_transport.h"
#include "media/cast/net/cast_transport_config.h"
#include "media/cast/net/pacing/paced_sender.h"
#include "net/base/io_buffer.h"
#include "net/base/ip_endpoint.h"
#include "net/socket/diff_serv_code_point.h"
#include "net/socket/udp_socket.h"

namespace net {
class NetLog;
} // namespace net

namespace media {
namespace cast {

    // This class implements UDP transport mechanism for Cast.
    class UdpTransport : public PacketTransport {
    public:
        // Construct a UDP transport.
        // All methods must be called on |io_thread_proxy|.
        // |local_end_point| specifies the address and port to bind and listen
        // to incoming packets. If the value is 0.0.0.0:0 then a bind is not
        // performed.
        // |remote_end_point| specifies the address and port to send packets
        // to. If the value is 0.0.0.0:0 the the end point is set to the source
        // address of the first packet received.
        // |send_buffer_size| specifies the size of the socket send buffer.
        UdpTransport(
            net::NetLog* net_log,
            const scoped_refptr<base::SingleThreadTaskRunner>& io_thread_proxy,
            const net::IPEndPoint& local_end_point,
            const net::IPEndPoint& remote_end_point,
            const CastTransportStatusCallback& status_callback);
        ~UdpTransport() final;

        // Start receiving packets. Packets are submitted to |packet_receiver|.
        void StartReceiving(
            const PacketReceiverCallbackWithStatus& packet_receiver) final;
        void StopReceiving() final;

        // Set a new DSCP value to the socket. The value will be set right before
        // the next send.
        void SetDscp(net::DiffServCodePoint dscp);

        // Set UdpTransport options.
        // Possible keys are:
        //   "pacer_max_burst_size": int
        //        - Specifies how many pakcets to send per 10 ms, maximum.
        //   "send_buffer_min_size": int
        //        - Specifies the minimum socket send buffer size.
        //   "DSCP" (value ignored)
        //       - Turns DSCP on (higher IP Precedence and Type of Service).
        //   "disable_non_blocking_io" (value ignored)
        //       - Windows only.  Turns off non-blocking IO for the socket.
        //         Note: Non-blocking IO is, by default, enabled on all platforms.
        void SetUdpOptions(const base::DictionaryValue& options);

        // This has to be called before |StartReceiving()| to change the
        // |send_buffer_size_|. Calling |SetUdpOptions()| will automatically call it.
        void SetSendBufferSize(int32_t send_buffer_size);

#if defined(OS_WIN)
        // Switch to use non-blocking IO. Must be called before StartReceiving().
        void UseNonBlockingIO();
#endif

        // PacketTransport implementations.
        bool SendPacket(PacketRef packet, const base::Closure& cb) final;
        int64_t GetBytesSent() final;

    private:
        // Requests and processes packets from |udp_socket_|.  This method is called
        // once with |length_or_status| set to net::ERR_IO_PENDING to start receiving
        // packets.  Thereafter, it is called with some other value as the callback
        // response from UdpSocket::RecvFrom().
        void ReceiveNextPacket(int length_or_status);

        // Schedule packet receiving, if needed.
        void ScheduleReceiveNextPacket();

        void OnSent(const scoped_refptr<net::IOBuffer>& buf,
            PacketRef packet,
            const base::Closure& cb,
            int result);

        const scoped_refptr<base::SingleThreadTaskRunner> io_thread_proxy_;
        const net::IPEndPoint local_addr_;
        net::IPEndPoint remote_addr_;
        std::unique_ptr<net::UDPSocket> udp_socket_;
        bool send_pending_;
        bool receive_pending_;
        bool client_connected_;
        net::DiffServCodePoint next_dscp_value_;
        std::unique_ptr<Packet> next_packet_;
        scoped_refptr<net::WrappedIOBuffer> recv_buf_;
        net::IPEndPoint recv_addr_;
        PacketReceiverCallbackWithStatus packet_receiver_;
        int32_t send_buffer_size_;
        const CastTransportStatusCallback status_callback_;
        int bytes_sent_;

        // NOTE: Weak pointers must be invalidated before all other member variables.
        base::WeakPtrFactory<UdpTransport> weak_factory_;

        DISALLOW_COPY_AND_ASSIGN(UdpTransport);
    };

} // namespace cast
} // namespace media

#endif // MEDIA_CAST_NET_UDP_TRANSPORT_H_
